id: consistent-existence-index-check
valid:
  - 'arr.includes(x)'
  - 'arr.indexOf(x) > 0'
  - 'arr.indexOf(x)'
invalid:
  - 'arr.indexOf(x) !== -1'
  - 'arr.indexOf(x) === -1'
  - 'arr.indexOf(x) >= 0'
  - 'arr.indexOf(x) < 0'